Field of the Invention
The present invention relates to a conductive polymer composition containing a π-conjugated conductive polymer, a coated article using the same, and a patterning process. Specifically, the present invention relates to a conductive polymer composition that is suitably used for prevention of electrification of a resist in lithography using ultraviolet light, electron beam, or the like; a coated article having an antistatic film formed by using the same; and a patterning process using the conductive polymer composition.
Description of the Related Art
Conventionally, in the fabrication process of a semiconductor device such as IC and LSI, microprocessing by lithography using a photoresist has been employed. This is a method of etching a substrate by using a resist pattern as a mask, in which the resist pattern is obtained by irradiating a thin film with light to induce crosslinking or decomposition reaction, thereby changing the solubility of the thin film, and subjecting the same to development treatment with a solvent or the like. In recent years, as a semiconductor device advances toward high integration, high-precision microprocessing using a beam with short wavelength have been required. The development of lithography using electron beam has been progressed for next generation technique because of its short-wavelength properties.
The lithography using electron beam has a specific problem of electrification phenomenon (charge-up) during exposure. This is a phenomenon that when a substrate to be irradiated with electron beam is coated with an insulating resist film, it is charged by accumulation of electric charge on or in the resist film. An orbit of incident electron beam is bent by the electrification, and therefore the precision of drawing is significantly reduced. Accordingly, an antistatic film to be applied on an electron beam resist has been investigated.
In the lithography using an electron beam, accurate positioning has been more important in an electron beam-drawing of a resist due to miniaturization to <10 nm generation. As the drawing technology, it has been developing higher electric current in prior arts, MBMW (multi beam mask writing), and so on, and it is presumed that the resist will be electrified more severely thereby. Accordingly, a conductive polymer with lower resistivity and higher ability to release the charge is required as a means to improve the antistatic performance of an antistatic film coping with the development of drawing technology from now on.
In order to suppress lowering of drawing accuracy due to electrification on a resist, Patent Document 1 discloses that the resist is coated with a π-conjugated conductive polymer having an introduced acidic substituent in the structure, and thus formed conductive polymer film shows an antistatic effect in electron-beam drawing, thereby dissolving various faults due to electrification such as a deformation of a resist pattern or an electrostatic adverse effect to accurate positioning of lithography in an electron beam irradiation. It is also revealed that the conductive polymer film retains water solubility even after electron beam-drawing with high irradiation dose, and accordingly can be removed by water washing.
Patent Document 2 discloses a composition composed of a polyaniline-based conductive polymer, polyacid, and H2O; and reveals that when the composite composed of a polyaniline-based conductive polymer and polyacid is 5 to 10% by mass, film forming by spin coating can be performed, and in addition to this, when the film thickness is 150 nm, antistatic performance is observed, and the antistatic film thus formed can be peeled and washed with H2O.